Eddie, there are just many, many railroad tie retaining walls in this area, and I guess they last quite awhile, but every time I go by one, I wonder why anyone would use them for a retaining wall when you
know it's going to have to be rebuilt some day.
I believe it was 1973 when I got a bunch of ties and used for a flower bed border across the front of the house, and a border in the back yard which I filled with gravel for a parking place for a little motorhome. At least, when they're lying on top of the ground, they're easy to replace.

But I sold that house in 1977 so didn't have to replace any, but I sure would not do it again.